The prior art contains several examples of corrosion resistant pipe having an ordinary carbon steel medial length integrally connected to opposed corrosion resistant alloy steel end members, thereby providing a bi-metal pipe section, such as seen in the prior patents to SAMPLE, 2,088,763; LOMAX, 4,679,294 and LULA, 4,366,971, for example.
The present invention patentably differs from the prior art and is advantageously used in manufacturing pipe sections that constitute an improvement over the type seen in the prior art references by the provision of an improved pipe section having opposed threaded ends; the marginal opposed threaded ends of which have a limited length thereof replaced with a stainless steel annular member. The stainless steel annular member is axially aligned with respect to the central longitudinal axis of the pipe section, and is made an integral part of the pipe section. The outer surface of the annular member is threaded such that the resultant new threaded surface coincides with and is an uninterrupted continuation of the original threads that remain on and extend along the old part of the pipe section.
This improved corrosion resistant pipe section unexpectedly results in a method of repairing old pipe sections wherein the resultant product is superior to the original pipe section. The new improved pipe section can be set down on the opposed ends thereof without damaging the corrosion resistant features thereof for the reason that the corrosion resistant features are achieved by substituting an annular stainless steel alloy for a short marginal opposed end of the ordinary carbon steel pipe length and therefore there is no need to rely on an internal plastic coating or otherwise sealing the pipe ends in order to isolate the underlying metal from the deleterious effects of corrosive fluid with which it is brought into contact.